Customarily, molten metal having a melting temperature in the area bove 1,400.degree. C. is cast into ingot molds and permitted to solidify in the form of ingots which are then reheated and rolled to desired shapes and cross-sectional dimensions. The ingot molds are made of cast iron and have thick walls. Such a mold during its service life tends to develop cracks on its inside surface and requires replacement if ingots having good surfaces are to be produced. These heavy cast iron ingot molds are expensive and difficult to manipulate.
It is impractical to make such ingot molds in small cross-sectional sizes. Therefore, the ingots they produce are of correspondingly large cross-sectional size and require undesirably extensive rolling to reduce them to the desired extent. The reheating of such large ingots, required for their rolling, is slow and expensive.
Heretofore it has been believed to be impossible to reduce the wall thickness of such cast iron ingot molds because their service life has been believed to be a function of the ratio of mold weight to ingot weight.
The continuous steel casting practice eliminates the need for using heavy cast iron ingot molds but requires extremely expensive machinery. This practice is limited to large steel producers.